fix(api): better check in documentation and add types

lua/care/init.lua

@@ -34,7 +34,7 @@ care.api = {
         return care.core and care.core.menu and care.core.menu:docs_visible()
     end,
     get_documentation = function()
-        return care.core.menu:docs_visible()
+        return (care.core and care.core.menu and care.core.menu:docs_visible())
                 and vim.api.nvim_buf_get_lines(care.core.menu.docs_window.buf, 0, -1, false)
             or {}
     end,

lua/care/types/api.lua

@@ -56,8 +56,12 @@
 --- indicates the visible position in the menu.
 ---
 --- This is really useful to create shortcuts to certain entries like in the
---- [example in configuration recipes](/configuration_recipes#labels-and-shortcuts).
+--- [Example usage](/configuration_recipes#labels-and-shortcuts).
 ---@field select_visible fun(index: integer): nil
 --- Indicated whether the menu is reversed
 --- Only relevant when using sorting direction "away-from-cursor"
 ---@field is_reversed fun(): boolean
+--- Get the documentation of the currently selected entry.
+--- Will return an empty table if no documentation is available.
+--- [Example usage](/configuration_recipes#access-documentation)
+---@field get_documentation fun(): string[]